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Biodiversity and the Future of Farming

May 28, 2013
Crop-Diversity2

A diverse, intercropped field

A story carried by the Huffington Post yesterday suggested that the pace of biodiversity loss was increasing as a result of economic forces and global climate change, threatening the future of farming and ranching.

It’s widely acknowledged that our dietary preferences are becoming increasingly narrow. Of the estimated 30,000 edible plants, just 30 account for 95 percent of human consumption, and just three (rice, wheat, and maize) account for 60 percent of human calories and protein derived from plants. At the same time, many traditional breeds of cows, sheep, and goats have fallen out of favor as new, higher yielding breeds are developed. But in the process, the genetic diversity of the species declines, making future generations more susceptible to disease.

Similarly, we know that the genetic diversity of agriculture has been in sharp decline over the past century. Indeed, according to the Food and Agriculture Organization, some 75 percent of the genetic diversity of agricultural crops was lost in the twentieth century. The primary force driving this process, they note, is the adoption of uniform, commercial crop varieties in place of traditional, more diverse varieties. As farmers adopted new varieties of crops with higher yields, traditional varieties disappear from farmers’ fields and ultimately die out. The genetic information they contain is lost forever.

We know the risks of genetic uniformity. Monocultures are expensive (in terms of chemical inputs) and are at greater risk of destruction from disease or pest attack. Further, we will never know precisely what traits we lose when a crop variety dies out. Perhaps the variety lost contained a trait that made it resistance to a particular disease. As the FAO report acknowledges,

During the 1970s the grassy-stunt virus devastated rice fields from India to Indonesia, endangering the world’s single most important food crop. After a four-year search which screened over 17 000 cultivated and wild rice samples, disease resistance was found. Only one population of the species Oryza nivara, growing wild near Gonda in Uttar Pradesh, was found to have a single gene for resistance to grassy-stunt virus strain 1. Today, resistant rice hybrids containing the wild Indian gene are grown across 110 000 km2 of Asian rice fields.

In the developing world, crop genetic diversity enables farmers to select crops suited to ecological needs and cultural traditions. Without this diversity, options for long-term sustainability are lost. This is particularly true in marginal areas with highly varied environments. The variety to a large extent determines the need for fertilizers, pesticides and irrigation. Communities that lose traditional varieties, adapted to local needs and conditions over centuries, risk becoming dependent on external sources of seeds and the inputs needed to grow and protect them. Without an agricultural system in harmony with a community and its environment, self-reliance in agriculture is impossible.

And therein lies the risk of biodiversity loss.

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